An Etymological Dictionary of Astronomy and Astrophysics

Geology: A → sedimentary particle that is between 4 and 64 mm in size. Pebbles are larger than → granules but smaller than → cobbles. Pebbles have typically been rounded by → abrasion during sedimentary transport (geology.com/dictionary).

Etymology (EN): From M.E. pibel, from O.E. *papol, *pyppel, *pæbbel, of unknown origin.

Etymology (PE): Rig, from Mid.Pers. rik “pebble, sand.”